In April, the weather in Terrance B. Lettsome International Airport is typically warm. Average daily high temperature in April is about 26 degrees above zero. On average, Terrance B. Lettsome International Airport has 20 sunny, 8 partly cloudy, and 2 rainy days in April. The rains are usually light. April as well as January, February, and March is considered the most comfortable time to visit Terrance B. Lettsome International Airport.